Babies Born in Fall Have Higher Risk of Developing Asthma

Are you concerned about having a baby with asthma? Well, you may want to hold off on when to conceive. A new study has shown that children born about four months before the height of the cold and flu season are at a higher risk of developing asthma.

“Infant age at the winter virus peak following birth independently predicts asthma development, with the highest risk being for infants born approximately four months prior to the peak, which is represented by birth in the fall months in the Northern hemisphere. Birth during this time conferred a nearly 30 percent increase in odds of developing asthma,” said Tina V. Hartert, M.D., M.P.H., associate professor of medicine and director of the center for Asthma Research at Vanderbilt University, and principal investigator of the study.

Researchers studied the medical records of more than 95,000 children and their mothers in the state of Tennessee. They wanted to determine whether the date of birth had any relationship to developing asthma.

They found that all babies were at an increased risk of developing asthma if they had bronchiolitis, but autumn babies were at the highest risk. They were able to show that the timing of birth and the risk of developing asthma moves in time with the peak of the cold and flu season each winter.

The researchers offer two possible reasons for this link. One being that genetic risk factors predispose children to asthma and the other possible cause is that environmental exposure, such as a winter viral infection, may cause asthma.

“The risk of progressing from bronchiolitis to asthma is almost certainly influenced by genetic factors,” wrote Dr. Hartert. “However, if this association were due only to genetic factors, there would be a seasonal effect on infection but not on asthma…Instead we have shown that there is variation in the risk of developing asthma by the timing of birth in relationship to the winter virus peak for each year studied. This supports a causal relationship of childhood asthma with the winter virus peak after birth.”

While the peak of the winter virus season is often difficult to determine because it varies each year, for families with children that are at high risk for asthma there are a few things that can be done to reduce the risks, one being to time the birth in the spring months.

While no asthma vaccine currently exists, Dr. Hartert notes that: “The next critical step is support for studies designed to determine whether prevention of the ubiquitous infections during infancy prevents childhood asthma.”

This research was published in the December issue of the American Journal of Respiratory and Critical Care Medicine.